Watch List notes:

Gallienus. A.D. 253-268. AE antoninianus (20.8 mm, 2.61 g, 1 h). Rome mint, struck A.D. 267-268. GALLIENVS AVG, radiate head of Gallienus right / NEPTVNO CONS AVG, hippocamp swimming right, N in exergue. Göbl 743b; RIC 245; RSC 667. Fine, some roughness.

Part of Gallienus' popular "zoo series" of coins struck to invoke the protection of Apollo against the revolt of Aureolus. He should have invoked the protection against his own generals however, as he was killed by his own soldiers on his way to meet Aureolus on the battlefield.